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2023.06.16

Flow Annealed Kalman Filters: Gradient-free inference for expensive forward models

<p>For many scientific applications the forward model consists of an expensive black-box simulator without easy access to gradients of the forward model. In such a situation, inference can be challenging, with standard gradient-free sampling algorithms requiring an intractably large number of serial model evaluations. In this talk I will introduce the flow annealed Kalman filter for approximate Ba...</p>

2023.06.09

3D Structure and Extinction of Nearby Molecular Clouds

<p>The 3D structure and extinction law are studied for the Taurus, Orion, Perseus and California molecular clouds (MCs) based on the LAMOST and APOGEE spectroscopy. Extinctions are calculated from color excess derived from the Blue Edge methods. In combination with the distance from the Gaia, &nbsp;a 3D extinction map and the structure of these MCs can be retrieved and the clouds that overlap in the sk...</p>

2023.06.02

A LOFAR Look at Bent Double Lobed Radio Sources: Probing Differences in the Properties of Bent Radio AGNs Inside and Outside of High-z Galaxy Clusters

<p>Bent radio AGN, with their classic “C” shaped morphology, are a unique class of radio AGNs. These radio sources are often used as signposts of a dense, gaseous medium, such as the intracluster medium (ICM). However, bent sources are found inside and outside cluster environments, raising the question of how environment impacts bent radio AGN morphology. We analyzed new LOw-Frequency Array Two-...</p>

2023.05.26

The Long-term Monitoring Results of Insight-HXMT in the First 4 yr Galactic Plane Scanning Survey

<p>The first X-ray source catalog of the Insight-HXMT Galactic Plane (∣b∣ &lt; 10°) Scanning Survey (GPSS) is presented based on the data accumulated from 2017 June to 2021 August. The 4 yr limit sensitivities at main energy bands can reach 8.2 × 10-12 erg s-1 cm2 (2-6 keV), 4.21 × 10-11 erg s-1 cm2 (7-40 keV), and 2.78 × 10-11 erg s-1 cm2 (25-100 keV). More than 1300 sources have been monitored at...</p>

2023.05.12

The Evolution of All Stable Isotopes within Galaxies Across Cosmic Time

<p>In the past decade, Galactic Chemical Evolution (GCE) has flourished due to surveys like Gaia, LAMOST, and Galex, which have enabled detailed investigations of stellar abundances. Stellar nucleosynthesis has also made strides in calculating both stable and radioactive isotopes, including the heavy isotopes produced by rapid neutron-capture (r-process). However, the astrophysical sources of r-p...</p>

2023.04.28

Alternative theories of gravity and their tests using astronomy observations

<p>General relativity is currently the standard theory to describe gravity. It has passed all the tests in our Solar System and has been positively supported by astronomy observations including electromagnetic waves from neutron stars and gravitational waves from coalescing compact binary systems. But fundamentally it is incompatible with quantum theory, and there are also the large-scale observat...</p>

2023.04.21

A fast radio burst source at a complex magnetized site in a barred galaxy

<p>Fast radio bursts (FRBs) are highly dispersed, millisecond-duration radio bursts prevailing in the universe. Recent observations of a Galactic FRB suggest that at least some FRBs originate from magnetars, but it is unclear whether the majority of cosmological FRBs, especially the actively repeating ones, are produced from the magnetar channel. Until now, more than 800 FRBs have been detected by...</p>

2023.04.14

The environmental dependency of the stellar initial mass function

<p>The stellar initial mass function (IMF) is one of the most important assumptions applied in astronomical studies. The stellar populations in the local universe appear to have a universal and invariant IMF which has been adopted as the standard canonical IMF since 1955. However, observations in recent decays suggest that the IMF, in fact, varies in more extreme environments. In this talk, I wil...</p>

2023.04.07

Complicated life of massive stars: the effect of rotation and binarity

<p>Massive stars are crucial in our understanding of many areas of modern astrophysics. Despite considerable efforts, there remain numerous unanswered questions regarding the formation and evolution of massive stars. Young star clusters are ideal laboratories to gauge stellar theory, because they are believed to be ensembles of co-eval stars with identical initial chemical compositions. However, r...</p>

2023.06.08

Structure and dynamics of the local group galaxies

<p>As the expansion of the universe continues to accelerate, the internal secular evolution of galaxies becomes more important as the distance between galaxies generally increases. The largest galaxies in the local group provide an ideal laboratory due to their proximity to study the secular evolution processes driven by internal dynamical structures, such as a bar and spiral arms. I will review t...</p>